Redox active polymer devices and methods of using and manufacturing the same

ABSTRACT

The disclosed technology relates generally to apparatus comprising conductive polymers and more particularly to tag and tag devices comprising a redox-active polymer film, and method of using and manufacturing the same. In one aspect, an apparatus includes a substrate and a conductive structure formed on the substrate which includes a layer of redox-active polymer film having mobile ions and electrons. The conductive structure further includes a first terminal and a second terminal configured to receive an electrical signal therebetween, where the layer of redox-active polymer is configured to conduct an electrical current generated by the mobile ions and the electrons in response to the electrical signal. The apparatus additionally includes a detection circuit operatively coupled to the conductive structure and configured to detect the electrical current flowing through the conductive structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/710,367, filed May 12, 2015, which claims priority to U.S.Provisional Patent Application No. 61/992,772, filed May 13, 2014, U.S.Provisional Patent Application No. 61/992,781, filed May 13, 2014 andU.S. Provisional Patent Application No. 62/000,843, filed May 20, 2014,each of which is assigned to the assignee of currently claimed subjectmatter and incorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED R&D

This invention was made with government support under DE-AR0000459awarded by the Department of Energy. The government has certain rightsin the invention.

BACKGROUND Field of the Invention

The disclosed technology relates generally to devices comprisingconductive polymers and more particularly to tag devices comprising aredox-active polymer film, and method of using and manufacturing thesame.

Description of the Related Art

Conductive structures made from conductive polymer films are used in awide variety of applications and often offer advantages over theirmetallic counterparts. For example, conductive structures made fromconductive polymers can offer advantages in cost, flexibility, weight,form factor and ease of manufacturing to name a few. For example,conductive structures made from conductive polymer films can be used forconnecting, fastening and electromagnetic shielding, to name a fewapplications. Some conductive polymers comprise conjugated double bondswhich provide the electronic conduction. Redox-active polymers areconducting polymers comprising functional groups capable of reversiblytransitioning between at least two oxidation states wherein thetransition between states occurs through oxidation (i.e. electron loss)and reduction (i.e. electron gain) processes. In addition to redoxactivity provided by the redox center, some redox-active polymers may beelectrically conductive through the polymer chain (e.g. polyaniline).

SUMMARY

The disclosed technology relates generally to devices comprisingconductive polymers and more particularly to tag devices comprising aredox-active polymer film, and method of using and manufacturing thesame.

In one aspect, a tag apparatus comprises a substrate and a conductivestructure formed on the substrate. The conductive structure includes alayer of redox-active polymer film having mobile ions and mobileelectrons. The conductive structure further includes a first terminaland a second terminal configured to receive an electrical signaltherebetween, where the layer of redox-active polymer is configured toconduct an electrical current generated by the mobile ions and electronsin response to the electrical signal. The apparatus additionallycomprises a detection circuit operatively coupled to the conductivestructure and configured to detect the electrical current flowingthrough the conductive structure.

In another aspect, an active tag apparatus comprises an electrochemicalenergy storage device. The electrochemical storage device comprises afirst electrode layer comprising a first redox-active polymer havingmobile ions and mobile electrons and a second electrode layer comprisinga second redox-active polymer film having mobile ions and mobileelectrons. The first electrode has a first redox potential and thesecond electrode has a second redox potential higher than the firstredox potential. The electrochemical energy storage device additionallycomprises an electrolyte layer interposed between the first electrodelayer and the second electrode layer. The electrolyte layer includes aconductive polymer film configured to conduct ionic current by passingmobile ions therethrough between the first and second electrode layers,and the conductive polymer film is further configured to not conduct asubstantial amount of electronic current. The active tag apparatusadditionally comprises a load device operatively coupled to the storagedevice. Under a charge condition, the storage device is configured to becharged via an ionic current flowing through the electrolyte layerbetween the first electrode layer which is configured to be reduced andsecond electrode layer which is configured to be oxidized. Under adischarge condition, the first electrode layer is configured to beoxidized and the second electrode is configured to be reduced such thatan electronic current flows through the load device.

In another aspect, an active tag device comprises a conductive structurehaving a first terminal and a second terminal and configured to receivean electromagnetic signal therebetween, the conductive structurecomprising a redox-active polymer film having mobile ions and mobileelectrons and configured to conduct an electrical current generated bythe mobile ions and the mobile electrons in response to theelectromagnetic signal. The active tag device additionally comprises aconversion circuit configured to convert the electromagnetic signal intoa DC voltage. The active device further comprises a storage devicehaving a first electrode layer and a second electrode layer configuredto receive the DC voltage, the storage device further comprising anelectrolyte layer interposed between the first electrode layer and thesecond electrode layer. The electrolyte layer comprises a conductivepolymer film configured to pass mobile ions, and the storage device isconfigured to be charged in response to the DC voltage developed bymobile ions passing between the first and second electrode layers inresponse to the DC voltage.

These and other embodiments are described in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

Claimed subject matter is particularly pointed out in the concludingportion of the specification. However, organization and/or method ofoperation, together with certain objects, features, and/or advantagesthereof, may be better understood by reference to the following detaileddescription if read with the accompanying drawings in which:

FIG. 1A is a schematic illustration of an apparatus having conductivepolymers according to some embodiments.

FIG. 1B is a schematic illustration of an apparatus having conductivepolymers according to some other embodiments.

FIG. 2 is a schematic illustration of an apparatus having conductivepolymers according to some other embodiments.

FIG. 3 is a schematic illustration of an apparatus having conductivepolymers according to some other embodiments.

FIG. 4 is an illustration of a tag device having conductive polymersaccording to some embodiments.

FIG. 5 is an illustration of a tag device having conductive polymersaccording to some other embodiments.

FIGS. 6(a) and 6(b) depict an electrochemical cell comprising a negativeelectrode comprising an n-type polymer and a positive electrodecomprising a self-compensated p-type polymer which includes azwitterionic polymer unit, undergoing electrochemical redox processesduring (a) a discharge operation and (b) a charge operation,respectively, according to some embodiments.

FIGS. 7(a) and 7(b) depict an electrochemical cell comprising a negativeelectrode comprising a self-compensated n-type polymer including azwitterionic polymer unit and a positive electrode with a p-typepolymer, undergoing electrochemical redox processes during (a) adischarge operation and (b) a charge operation, respectively, accordingto some other embodiments.

FIGS. 8(a) and 8(b) depict an electrochemical cell comprising a negativeelectrode comprising a first self-compensated p-type polymer including afirst zwitterionic polymer unit and a positive electrode comprising asecond self-compensated p-type polymer including a second zwitterionicpolymer unit, undergoing electrochemical redox processes during (a) adischarge operation and (b) a charge operation, respectively, accordingto yet some other embodiments.

FIG. 9 depicts an electrochemical cell comprising a negative electrodecomprising an n-type polymer and a positive electrode comprising aself-compensated p-type polymer which includes a zwitterionic polymerunit, undergoing electrochemical redox processes during a dischargeoperation and a charge operation, according to some embodiments.

FIG. 10 illustrates cyclic voltammograms showing current-voltagecharacteristics of an electrochemical cell comprising a self-compensatedpolymer which includes a zwitterionic polymer unit, according toembodiments.

FIG. 11 illustrates chronoamperiometric curves showing current-time andcharge-time characteristics of an electrochemical cell comprising aself-compensated polymer which includes a zwitterionic polymer unit,according to embodiments.

FIG. 12A illustrates cyclic voltammograms showing current-voltagecharacteristics of an electrochemical cell comprising an uncompensatedpolymer.

FIG. 12B illustrates cyclic voltammograms showing current-voltagecharacteristics of an electrochemical cell comprising a self-compensatedpolymer which includes a zwitterionic polymer unit, according toembodiments.

DETAILED DESCRIPTION

Electrically conductive polymers are organic polymers often comprisingconjugated double bonds which provide electronic conduction properties(e.g. polyacetylene). Redox-active polymers are polymers comprisingfunctional groups capable of reversibly transitioning between at leasttwo oxidation states wherein the transition between states occursthrough oxidation (i.e. electron loss) and reduction (i.e. electrongain) processes. In addition to redox activity provided by the redoxcenter, redox-active polymers may be electrically conductive through thepolymer chain (e.g. polyaniline). For the purposes of the followingdescription, the term “redox-active polymer” may be used interchangeablywith the term “redox polymer” to describe conductive redox-activepolymers.

Conductive structures made from conductive polymer films are used in awide variety of applications and often offer advantages over theirmetallic counterparts, including lower cost, flexibility, lower weight,lower form factor and ease of manufacturing. Examples of suchapplication can include electronic components such as an antenna, aresistor, an inductor, a capacitor, a diode, a light-emitting elementand a transistor, to name a few. Other example applications includeconductive tags, tag devices and adhesive members. Conventionally, suchdevices can be made from thin metallic materials, or from nonconductivemedium such as polymeric sheets having metallic or other conductiveelements in the form of a metallic paint, metallic tape or metallic orcarbon fiber, nanotube and/or particle forming a conductive networktherein and/or thereon. The nonconductive medium which includes themetallic or other conductive elements can be, for example, a polymerlayer and/or matrix e.g. epoxy, vinylester, polyester, thermoplasticand/or phenol formaldehyde resin to name a few.

One particular application of conductive polymers can include a tagdevice. As used herein, a tag broadly refers to any conductive structurethat may be affixed to a parent structure for the purpose of providing,for example some information about the parent structure. A tag can be,for example, an adhesive, a label, a sticker, an identification tag or aradio frequency identification (RFID) tag, to name a few examples. Theinformation can be any information, such as a product information (e.g.location, age, etc.) and environmental information (temperature,humidity, etc.), among other types of information.

The tag may be adhered to a parent object or structure via an adhesive,printing, electrodeposition or other adhering process. The location,identification and flow of assets (e.g. consumer products, merchandise,inventory, goods, animals, etc.) are often monitored by affixing a tagto the parent object. Commonly, radio-frequency identification (RFID)tags are affixed to a parent object for monitoring its relatedinformation which may be stored in a memory component (e.g. microchip)of the RFID tag. A suitable electromagnetic field may be employed toread and/or change information related to the parent object. PassiveRFID tag devices are limited by the strength and radius of theinterrogative electromagnetic field and consequently limited to shortcommunication ranges and data tracking time periods. Active RFID tagshave energy storage capability which overcomes the limitations relatedto passive tags, however they are limited in expense, complexity andsize.

Labels, stickers, radio frequency identification (RFID) tags and otheradhesive products are used for communicating information either inwriting or electromagnetically. These systems are also often used as theprimary or secondary fastening systems in consumer and automotiveelectronics and various types of enclosures. For example, identificationtags may be affixed to a product for the purpose of inventory control.Conventional active and semi-passive tags are prohibitively expensivefor low-cost applications and products. Currently, active andsemi-passive tags are too expensive for low-cost item inventory controldue to the cost of the energy storage component. Conventional activetags typically comprise a battery which powers microchip circuitry.Additionally, active tags may employ batteries to power an antenna forsignal broadcast. Semi-passive tags typically comprise a battery topower microchip circuitry, however interrogative electromagnetic wavesinduce an antenna current for signal broadcast.

Conventional low-cost passive tags do not comprise a battery or energystorage means. Passive tags operate via a backscatter mechanism whereinan incoming interrogative waveform is modulated by the tag and reflectedback to a reader. There are several drawbacks of conventional low-costpassive tags including restricted signal ranges, limited “active” timeperiods and low signal-to-noise ratios due to the absence of an energystorage component.

Thus, there is a need for tag devices and other similar devices madefrom conductive polymers which can offer existing benefits of tags madefrom other materials, which can also be integrated with low cost energystorage devices such as thin film batteries. The current limitations ofboth active and passive tags may be overcome by employing embodiments ofthe tag devices described herein. For example, in various embodimentsthe tag devices are simple, low cost energy storage systems which arereadily manufacturable. The polymer tag may be employed forcommunication, identification, shielding, connecting, fastening and/orany other suitable application.

Referring to FIG. 1A, a tag apparatus 10 comprises a substrate 12 and aconductive structure 14 formed on the substrate 12 according to someembodiments. The conductive structure 14 includes a layer ofredox-active polymer film having mobile ions (M+/−) and electrons (e−).The conductive structure 14 further includes a first terminal 16 and asecond terminal 18 configured to receive an electrical signal 22therebetween, where the layer of redox-active polymer is configured toconduct an electrical current (I) generated by the mobile ions and theelectrons in response to the electrical signal. The apparatusadditionally comprises a detection circuit 20 operatively coupled to theconductive structure 14 and configured to detect the electrical current(I) flowing through the conductive structure 14.

In the illustrated tag apparatus 10 of FIG. 1A, the conductive structure14 can include at least one electronic component selected from the groupconsisting of an antenna, a resistor, an inductor, a capacitor, a diode,a light-emitting element and a transistor.

In one embodiment, the tag apparatus 10 is a passive identification (ID)tag and the conductive structure 14 comprises an antenna having thefirst and second terminals 16 and 18 configured to receive theelectrical signal 22, in the form of an electromagnetic (EM) electricalsignal. For example, the tag apparatus 10 can be a passive radiofrequency identification (RFID) device having the conductive structure14 comprising an antenna configured to receive a radio frequencyelectromagnetic electrical signal.

In embodiments where the tag apparatus 10 is an ID tag, an electroniccomponent selected from the group consisting of a resistor, a capacitor,a diode and a transistor, or a combination thereof, can be used to storeidentification information. As used herein identification informationcan be any information, such as that which may be stored in an ID tag.

Still referring to FIG. 1A, the detection circuit 20 can include atleast one of a voltage detection circuit or a current detection circuitthat is electrically connected and is integrated on the same substrate12 as the conductive structure 14. The detection circuit 20 can beconfigured to detect the identification information from the conductivestructure 14. In embodiments where the tag apparatus 10 is a passive IDtag, e.g., a passive RFID tag, the detection circuit 20 can include anyone or more circuit components in RFID chips that are used for detectingthe identification information, whose description can be found, forexample, in U.S. Pat. No. 6,700,491 (hereinafter '491 patent), which ishereby incorporated by reference in its entirety, and particularly forthe purpose of describing such components and chips.

In some embodiments, the detection circuit 20 can be configured todetect a change in electrical conductivity of the redox-active polymerof the conductive structure 14 in response to a change in thetemperature of the conductive structure 14 of 1° C. or greater, 5° C. orgreater, or 10° C. or greater. In other embodiments, the detectioncircuit 20 is configured to detect a change in electrical conductivityof the redox-active polymer of the conductive structure 14 in responseto a change in the relative humidity surrounding the conductivestructure of 1% percent or greater, 5% percent or greater, or 10%percent or greater. In embodiments where the detection circuit 20 isconfigured to detect a change in electrical conductivity of theredox-active polymer in response to a change in the relative humidity,the layer of redox-active polymer can include a hygroscopic additiveselected from the group consisting of chloride salts, sulfate salts,nitrate salts and/or organic salts to enhance the detection capabilityof the moisture.

Advantageously, in some embodiments, the detection circuit 20 comprisesa layer of redox-active polymer film that integrally extends from thelayer of redox-active polymer film of the conductive structure 14. Thatis, at least portions of the detection circuit 20 and the conductivestructure 14 can comprise the same layer of the conductive structure 14.

While in FIG. 1A, the detection circuit 20 is integrated with theconductive structure 14 on the same substrate 12, other arrangements arepossible, as illustrated in a tag apparatus 30 of FIG. 1B. The tagapparatus 30 of FIG. 1B is similar to the tag apparatus 10 of FIG. 1A,except that the detection circuit 24 is physically separated from thesubstrate 12, on which the conductive structure 14 is formed. Forexample, the detection circuit 24 can comprises one of a voltagedetection circuit or a current detection circuit that is physicallyseparated from the substrate. The detection circuit 24 can be configuredto receive electromagnetic signal such as an electromagnetic signal(e.g., RF signal), for example, where the conductive structure 14 isconfigured to emit an electromagnetic signal. The detection circuit 24can also be configured to receive photons (e.g., visible or infraredphotons), for example, where the conductive structure 14 is configuredto emit photons. In other embodiments, the detection circuit 24 can beconfigured to contact certain points of the conductive structure 14 orterminals.

Referring to FIG. 2, an active tag apparatus 50 comprises anelectrochemical energy storage device 32. The electrochemical storagedevice 32 comprises a first electrode layer 34 comprising a firstredox-active polymer having mobile ions and mobile electrons and asecond electrode layer 36 comprising a second redox-active polymer filmhaving mobile ions and mobile electrons. The first electrode 34 has afirst redox potential and the second electrode 36 has a second redoxpotential higher than the first redox potential. The electrochemicalenergy storage device 32 additionally comprises an electrolyte layer 38interposed between the first electrode layer 34 and the second electrodelayer 36. The electrolyte layer 38 includes a conductive polymer filmconfigured to conduct ionic current by passing mobile ions therethroughbetween the first and second electrode layers 34 and 36, and theconductive polymer film is further configured to not conduct asubstantial amount of electronic current. The active tag apparatus 50additionally comprises a load device 40 operatively coupled to thestorage device 32. Under a charge condition, the storage device 32 isconfigured to be charged through an ionic current flowing through theelectrolyte layer between the first and second electrode layers 34 and36. Under a discharge condition, the first electrode layer 34 isconfigured to be oxidized and the second electrode 36 is configured tobe reduced such that an electronic current flows through the load device40.

Still referring to FIG. 2, in some embodiments, the active tag apparatus50 is an active ID device having an antenna configured to receive andtransmit an electromagnetic electrical signal using energy from thestorage device 32, where the active tag device 50 further comprises aconductive structure 14 having a first terminal 16 and a second terminal18 and configured to receive an electromagnetic signal 22 therebetween.The conductive structure 14 comprises a redox-active polymer film havingmobile ions (M+/M−) and electrons (e−) and configured to conduct anelectrical current generated by the mobile ions (M+/M−) and theelectrons (e−) in response to the electromagnetic signal 22. In theseembodiments, the active tag apparatus 50 additionally comprises aconversion circuit 42 configured to convert the electromagnetic signal16 into a DC voltage. The electrochemical energy storage device 32 isconfigured to be charged in response to the DC voltage developed bymobile ions passing between the first and second electrode layers 34 and36 in response to the DC voltage.

Still referring to FIG. 2, in some embodiments, the load device 40comprises an electromagnetic wave transmission device, such as an RFtransmitter. In other embodiments, the load device 40 comprises anelectroluminescent device, such as a photodiode. In some embodiments,the electroluminescent device comprises at least one of the first andsecond redox-active polymer films of the electrochemical energy storagedevice 32.

In some other embodiments, the load device 40 comprises an ID chipconfigured to transmit identification information. In some embodiments,the load device 40 comprises an RFID chip which can include any one ormore circuit components in RFID chips that are that are commonlyincluded in such chip, whose description can be found, for example, inthe '491 patent.

In some embodiments, by choosing a value of impedance or the resistanceof the load device, along with a combination of the combination ofredox-active polymers having the properties described herein, the loaddevice can be configured to dissipate substantially the energy stored inthe storage device 32 within a predetermined time period. That is, thetag apparatus can be configured to have an active time period duringwhich an electromagnetic or a light signal can be transmitted. This timeperiod can be altered based on the size, number of layers, redox-activepolymer chemistry. For example, the load device is configured totransmit an electromagnetic signal or a light signal for a predeterminedtime period between about 10 seconds and about 24 hours, or betweenabout 1 day and 10 days, or between about 10 days and about 1 year. As anon-limiting example, depending on the application, the tag apparatusmay be configured as a small (e.g. <1 cm²), single layer redox polymerfilm having a low characteristic charge capacity (e.g. <100 Ah/kg).Alternatively, for applications suitable for longer “active” timeperiods, the tag apparatus may be configured as a larger (e.g. >100 cm²)multi-layer (e.g. >3 layers) system comprising redox polymer with highcharacteristic charge capacities (e.g. >300 Ah/kg). For example, a 1 cm²tag having a thickness of 300 μm with an energy density of 100 Wh/Lprovides enough power to operate a RFID label for several read cycles orcontinuously power antenna signal of 100 mW for almost 2 minutes. Asanother non-limiting example, a 25 cm² tag having a thickness of 0.2 cm(five layers of 300 μm thick cells) with an energy density of 300 Wh/Lprovides enough power to operate a label for over 10 hours.

In the following, referring to FIG. 3, an electrochemical cell 100,similar to the electrochemical storage device 32 of FIG. 2, is discussedin detail. The electrochemical cell 100 includes a negative electrode,or anode 110, which comprises a redox polymer having a standard redoxpotential Ea. The electrochemical cell 100 additionally includes apositive electrode, or cathode 120, which comprises a redox polymerhaving a standard redox potential Ec wherein Ec is generally morepositive than Ea. A solid-state ion-exchange polymer electrolyte orionically conductive polymer or gel 130 is situated between the anode110 and cathode 120 permitting ionic conduction between anode 110 andcathode 120. During discharge, the oxidation half-reaction may takeplace at the anode 110. The electrons produced in the oxidation processat the anode 110 may flow to a load 140 (associated with the device orapparatus) and return to the cathode 120 to facilitate the reduction ofthe redox polymer at the cathode 120. During the charge process via anexternal power source, the redox polymer at the anode 110 is reduced andthe redox polymer at the cathode 120 is oxidized.

In an embodiment, the thickness of the anode 110 and cathode 120 may beless than 200 μm, the ion-exchange polymer 130 may be less than 100 μmand the thickness of the cell 100 may be less than 500 μm. In anotherembodiment, the thickness of the anode 110 and cathode 120 may be lessthan 125 μm, the ion-exchange polymer 130 may be less than 50 μm and thethickness of the cell 100 may be less than 300 μm.

In an embodiment, the electrochemical cell 100 may comprise protectivecompounds functioning to protect redox polymers from over-charge and/orover-discharge. Over-discharge may result in irreversible reduction of apositive electrode redox polymer and/or irreversible oxidation of anegative electrode redox polymer. Likewise, over-charge may result inirreversible oxidation of a positive electrode redox polymer and/orirreversible reduction of a negative electrode redox polymer. Forexample, redox shuttles or any other suitable compounds may bereversibly reduced or oxidized instead of over-charging orover-discharging a redox polymer of the anode 110 or cathode 120. Theseprotective compounds may be present in the negative electrode, positiveelectrode or a combination thereof. Non-limiting examples of protectivecompounds include phenothiazine, iodine, tri-iodine, quinones (e.g.benzoquinones, naphthoquinones, and anthraquinones), their derivativesand combinations thereof.

In an embodiment, a redox polymer may be a constituent of a copolymer orpolymer blend. In addition to other properties, blending and/orcopolymerization may improve the mechanical stability of the electrodeduring fabrication and/or during long-term charge-discharge cycling.Some non-limiting examples of copolymer or polymer blends are describedbelow.

For example, a suitable polymer blend may be provided to enablethermoplastic manufacturing processes (e.g., thermoforming). Forexample, conductive polymers are generally not thermoplastics (e.g.,thermoformable) so a plasticizer (e.g. esters of polycarboxylic acids,phthalate esters and so on) and/or other suitable additives thatincrease plasticity or fluidity may be a component of a co-polymer orpolymer blend.

As another example, the redox-active polymer may have limited electricalconductivity alone. In an embodiment, a more conductive polymer may beblended or copolymerized with a redox-active polymer. In someembodiments, polymers with higher conductivities may also be redoxpolymers themselves. For example, linear-backbone “polymer blacks” likepolyacetylene, polypyrrole, and polyaniline may provide increasedelectrical conductivity. Non limiting examples include polyfluorenes,polyphenylenes, polypyrenes, polyazulenes, polynaphthalenes,polyacetylenes, polyphenylenevinylenes, polypyrroles, polycarbazoles,polyindoles, polyazepines, polyanilines, polythiophenes,polyphenylenesulfides, their derivatives and combinations thereof.

In some embodiments, it may be preferable to make the polymer film moreporous in order to facilitate the ion exchange of the polymer redoxstates. Ionic conductivity of an electrode may be improved with the useof any suitable additive providing increased free volume and/or porositywithin a polymer electrode. In some embodiments, the additive may be acomponent of a copolymer or polymer blend. For example, manufacturingmethods that incorporate porosity may include: incorporating bulky,contorted monomer structures resulting in inefficient polymer chainpacking (e.g. tetrahedral monomers), blending a redox-active polymerwith a second polymer which is soluble in a solvent, using gas phasefoaming agents, using chemically decomposing foaming agents, inducingphase separation in the presence of non-solvents, applying shearstresses sufficient to cause fibril formation and coalescence or anyother suitable method known in the polymer engineering arts. As anotherexample, the redox-active polymer may have limited mechanical stabilityalone. In an embodiment, a material providing increased mechanicalstability may be blended or copolymerized with a redox-active polymer.For example, two polymers may be blended to provide improved fiberrheology resulting in a relatively high degree of mechanical stability.In some embodiments, a separate membrane with high mechanical stabilitymay be provided in layers of the battery. As yet another example, aredox-active polymer may be blended with a polymer which providesimproved adhesion to a substrate. In some embodiments, it may bedesirable to improve adhesion to a current collector, separator and/orsome feature of the associated device or apparatus.

Still referring to FIG. 3, in an embodiment, the redox polymers may bein contact with a conductive sheet or film to provide increasedelectrical conductivity and/or mechanical stability. This may beperformed by any suitable method known in the art including lamination,film casting, film coating, electropolymerization, physical vapordeposition, and so on. For example, the redox polymer may be ametallized film wherein the redox polymer is coated on a thin layer ofmetal acting as a current collector. In some embodiments, the redoxpolymer may be in contact with a non-conductive sheet or film providingmechanical stability, as some feature of the device and/or as a generalseparator. In an embodiment, the system may comprise a plurality ofelectrochemical cells 100 formed in layers wherein the negativeelectrode or anode 110 of a first cell 100 is electrically connected toan anode of a second cell and the positive electrode or cathode 120 ofthe first cell 100 is electrically connected to a cathode of a thirdcell. Such a configuration may be repeated any suitable number of timesand numerous other arrangements are also possible, depending on thespecifics of the application.

In an embodiment, polymers may be synthesized by any suitable methodknown in the art, including but not limited to chemical oxidation orreduction, metal complex dehalogenation, metal complex coupling,step-growth polymerization, chain-growth polymerization,electropolymerization and so on.

Still referring to FIG. 3, in an embodiment, the electrochemical cell100 or plurality of electrochemical cells 100 and its associated device,apparatus or system (e.g. electric vehicles, consumer electronics etc.)may be manufactured by an injection molding process, additivemanufacturing process and/or any other suitable manufacturing method.

In an embodiment, the polymer may comprise dopants modifying theelectrical conductivity or other properties. The dopants may beincorporated into the redox polymers by any suitable method. Forexample, the dopants may include charged species which may beincorporated during electrochemical oxidation and/or reductionprocesses. In a feature of an embodiment, oxidative and/or reductivedoping may improve the electrical conductivity of the redox polymer. Insome embodiments, the redox polymer may be activated before or aftercell 100 assembly. For example, the redox polymer may be oxidized orreduced before integration into cell 100 in an ionically conductivemedium comprising preferred dopant species, if any.

In an embodiment, the redox polymer structure may comprise anelectrically conductive polymer backbone with functional side groupshaving redox activity. In some embodiments, the redox polymer may have astructure wherein the preferred redox-active groups are part of a mainelectrically conductive polymer chain. The polymer includes aredox-active group that can exist in at least two oxidation states. Inan embodiment, redox-active groups of the organic polymer may comprisecyclic or acyclic heteroatoms including but not limited to O, S, N, P,transition metals, metallocenes and combinations thereof. For example,the redox-active groups may include cyclic, polycyclic and/or acyclicstructures comprising alkanes, alkenes, benzenes, styrenes, alcohols,ketones, esters, ethers, amines, amides, imines, imides, alkylamines,pyridines, thiols, thiophenes, thiones, thials, phenothiazines,sulfides, sulfoxides, phosphines, phosphones, halides, quinones, theirderivatives and combinations thereof.

In an embodiment, the redox-active group may form quinoid structures.For example, structures may include benzoquinones, naphthoquinones,anthraquinones, hydroquinones, aminoquinones, polyvinylquinones,polycyclic quinones, their derivatives or combinations thereof.

Referring now to FIG. 4, a tag device 102 comprises a first anode, or anegative electrode, layer 110. The tag device may store and deliverenergy via electrochemical redox processes. The first anode layer 110comprises a redox-active polymer film is capable of being oxidizedduring a discharging operation of the tag device 102. The first anoderedox-active polymer of first anode layer 110 may be characterized by afirst redox potential. A second cathode, or positive electrode, layer120 comprises a redox-active polymer film capable of being reducedduring a discharging operation. The second cathode redox-active polymermay be characterized by a second redox potential. An electrolyte layer130 is situated between the first anode layer 110 and second cathodelayer 120. The electrolyte layer 130 comprises an ionically conductivepolymer film for conducting ions between the first anode layer 110 andsecond cathode layer 120. The electrolyte layer 130 may be solid-stateor in some embodiments, may be a gel. The electrolyte layer 130 does notconduct a substantial amount of electronic current.

In some embodiments, the redox-active polymers are selected toreversibly store electrochemical energy. During a charging operation,the anode redox-active polymer is capable of being reversibly reducedand the cathode redox-active polymer is capable of being reversiblyoxidized. The presence of an electromagnetic field may provide the powerfor the charging operation via induction. In some embodiments,redox-active polymers may be provided in the form of an induction coil.

The negative electrode and positive electrode redox active polymers maybe selected from the group of substituted or unsubstitutedpolyacetylenes, polypyrroles, polyanilines, polyphenylenes, polypyrenes,polyazulenes, polynaphthalenes, polyphenylenevinylenes, polycarbazoles,polyindoles, polyazepines, polythiophenes, polyphenylenesulfides,polymerized conjugated carbonyls, polymerized conjugated amines,polynitroxyls, polyorganodisulfides, polythioethers, electroluminescentorganic semiconductors, their derivatives, copolymers and combinationsthereof. In some embodiments, the polymer chemistries and systems may beselected from those disclosed in co-pending PCT ApplicationPCT/US2014/020874 entitled “Integrable redox-active polymer Batteries”which is incorporated herein by reference in its entirety, andparticularly for the purpose of describing anode and cathode redoxactive polymers.

Still referring to FIG. 4, the first anode layer 110 and the secondcathode layer 120 are both electronically conductive and ionicallyconductive. The electrolyte layer 130 is capable of conducting ionsbetween the first anode layer 110 and the second cathode layer 120;however, electrolyte layer 130 is not capable of electronic conduction.In an embodiment, the first redox potential associated with the firstanode layer 110 is lower than the second redox potential associated withthe second cathode layer 120. For example, the difference in redoxpotential between the anode and cathode polymers may be selected to begreater than 0.1 volt, e.g., greater than 0.5 volt or greater than 1.0volt. In some embodiments, the potential of the redox couples may begreater than 2 volts.

In an embodiment, the anode layer and cathode layer may comprise dopantsto maintain charge neutrality and/or modify the electrical conductivity.In some embodiments, the redox polymer may be activated before or afterassembly of the tag device. For example, the anode and cathode layersmay be initially manufactured in a doped state. For other applications,the anode and cathode layers may be initially manufactured in anundoped, or discharged, state.

Still referring to FIG. 4, in an embodiment, the thickness of the anodelayer 110 and cathode layer 120 may be less than 300 μm, the electrolytelayer 130 may be less than 100 μm. In some embodiments, the thickness ofthe anode layer 110 and cathode layer 120 may be less than 75 μm and theelectrolyte layer 130 may be less than 50 μm and in some embodiments,less than 10 μm. For simplicity, the illustrated embodiment of FIG. 1depicts a single anode layer 110, a single cathode layer 120 and asingle electrolyte layer 130; however any suitable number of layers maybe provided depending on the application. For example, the anode layerof a first cell is electrically connected to an anode layer of a secondcell and the cathode layer 120 of the first cell is electricallyconnected to a cathode layer of a third cell. Such a configuration maybe repeated any suitable number of times and numerous other arrangementsare also possible, depending on the specifics of the device, apparatusor system. In some embodiments, a plurality of layers may be provided.Furthermore, single tag devices may be provided singularly or be furtherintegrated with other films to form more complex tag devices.

Still referring to FIG. 4, the tag device 102 may further comprise aprotective layer 160. The protective layer 160 may be a non-conductingpolymer situated as the uppermost layer of the tag device 102. Forexample, the protective layer may comprise polyethylene, polypropylene,epoxy, polyester, derivatives or combinations thereof.

Still referring to FIG. 4, in some embodiments, the tag device 102further comprises an adhesive layer 150 for affixing the tag device 102to a parent object. In the illustrated embodiment of FIG. 4, the parentobject 170 may be a product or collection of products to which the tagdevice 102 is affixed for the purpose of inventory control. For example,the tag device 102 may be affixed to an inventory storage bin 170. Theproduct storage bin 170 may be stored in the presence of aradio-frequency electromagnetic field which continually energizes, orcharges, the tag device 102. When the product bin 170 is moved from thetransmitting radius of the radio-frequency electromagnetic field, thetag device 102 will continue to emit identification information while intransit. It may be appreciated that the stored electrochemical energymay be released over application-relevant time period. For example, thetag device 102 may be provided to emit identification information in therange of minutes to hours after being removed from the transmittingradius of the radio-frequency electromagnetic field. This time periodcan be altered based on the size, number of layers, redox-active polymerchemistry and desired operating conditions. As another example, an RFIDtag device affixed to a product may remain active for a designed timeperiod after scanning at a checkout counter, thus avoiding inventoryloss. The time period the tag remains active may be set based on thecharge density of the redox active polymer and/or the number of redoxactive polymer layers of the tag device. As yet another example, the tagdevice may comprise a conducting polymer with electroluminescentproperties. The tag device may be designed to glow for a predeterminedtime period after exposure to a radio-frequency electromagnetic source.

In some embodiments, the tag device comprising a conducting polymer isconfigured to electrically connect two components of a parent objectthat otherwise may only be in nominal electrical contact. In someembodiments, the conductive tag devices have the advantage of beingdie-cut into simple electronic circuits that are valuable for connectingmultiple electronic components by simple adhesion.

In some embodiments, the tag device may be designed to provide shieldingfrom electromagnetic interference, electrostatic discharge, radiofrequency interference or a combination thereof. For example, a thinlayer tag device may prevent electromagnetic damage of a parent objectto which it is affixed e.g. act as a simple Faraday cage. The tag devicemay be provided as an electrically conductive tape or adhesive employedas a low cost way to seal parent object components (e.g. automotiveproducts) and simultaneously prevent electromagnetic and/orelectrostatic damage to the parent object and/or parent object componentto which the tag device is affixed. The effectiveness of electromagneticinterference shielding is measured by the attenuation of the tag devicei.e. the ratio between field strength with and without the presence ofthe tag device. For example, the tag device may provide shieldinggreater than 10 dB. In some embodiments, the tag device may provideshielding greater than 50 dB.

The redox polymer systems may be selected based on a change in theirproperties due to environmental conditions. For example, the polymerfilm may be selected such that the charge transport processes within thefilm are significantly dependent on temperature i.e. the redox polymerresistance has strong dependence on temperature. Therefore one couldbuild a simple circuit that records the temperature history of a productto which it's affixed which has utility for applications related toperishable goods. As another example, there may be a parametricrelationship with relative humidity which may for example, be useful tosense the relative humidity history on electronics, etc.

Still referring to FIG. 4, in some embodiments, the tag device furthercomprises an auxiliary low power component (which may be a polymeritself or for example, a metal antenna or silicon ship). During adischarge process, energy is delivered to the low power component of thetag device. During discharge, an oxidation reaction takes place at theanode layer 110. The electrons produced in the oxidation process at theanode 110 may flow to a low power component associated with a low powercomponent associated with the tag device and return to the cathode layer120 to facilitate the reduction of the redox polymer at the cathodelayer 120. The tag component may be selected from the group of acircuit, an antenna, a memory chip or a combination thereof. The storedenergy is delivered to the low power tag component provided for thetransmission of wireless signals. Or alternatively, the stored energy isdelivered to the low power tag component provided for storage ofidentification information. Or alternatively, the stored energy isdelivered to the low power tag component provided for signal processing,analysis of environmental conditions or other valuable electronicapplications. In some embodiments, these components may be redox activepolymers.

In an embodiment, the redox-active polymers may be provided as part of acomposite tag device. A component of the composite may provide astructural feature, mechanical strength and/or a function relevant totag device operation. Components of the composite may be formed of anysuitable material (e.g. carbon, metal, glass and so on), any suitableshape (e.g. fibers, woven, whiskers, particles, porous matrix and soon), and may also provide any suitable function (e.g. mechanicalstrength, electrical conduction, ionic conduction, etc.). For example,the composite may comprise carbon fiber, fiber glass, metal whiskers,carbon particles, woven metals and or any other suitable material.

The tag device may be formed by a die-cutting manufacturing processwherein a shaped blade cuts a large polymer film sheet into smallerpredetermined shapes, the large polymer film sheet comprising the firstanode layer, the second cathode layer and the electrolyte layer. Otherlow cost film manufacturing approaches may be employed includingroll-to-roll processing, roll slitting to cut a larger film or roll intosmaller predetermined shapes, etc.

In an embodiment, additive manufacturing techniques may be employed toproduce a tag device in virtually any shape. For example, a digitalmodel of the tag device may be designed and successive layers may belaid down in a pattern corresponding to the model. For example,successive layers of an anode layer, an electrolyte layer, a cathodelayer, may be formed by a plurality of nozzles associated with anadditive manufacturing system.

An embodiment provides a method for manufacturing a tag device, whereinthe method comprising a first step of providing an anode layercomprising a redox-active polymer film. An electrolyte layer comprisingan ionically conductive polymer film for conducting ions may then beprovided such that a first side of the ionically conductive polymer filmcontacts a first side of the anode layer. A cathode layer comprising aredox-active polymer film may then be layered such that the second sideof the ionically conductive polymer contacts a first side of the cathodelayer. The resulting tri-layer sheet may then be cut into smallerpredetermined shapes.

In an embodiment, electrical circuit elements may be included or cutdirectly into the films. For example, the predetermined shapes may beany type of basic circuit element such as an antenna, a capacitor, aresistor, an inductor, a battery, an electroluminescent component and soon. Tag devices of varying complexity may be generated simply bylayering multiple sheets of thin layers comprising conductive and/orredox-active polymers followed by die-cutting into the predeterminedshape based on the desired application. As a simple example of a tagdevice 210 depicted in FIG. 5, a polymer battery 220 may comprise abattery element 220 comprising an anode layer, electrolyte layer and acathode layer. The tag device 210 may further comprise an antennaelement 230 which is shaped and adapted for the transmission ofelectromagnetic waves.

Still referring to FIG. 5, in some embodiments, the antenna element 230is a single layer comprising a conductive and/or redox polymer. In suchan embodiment, the battery element 220 and antenna element 230 may bemanufactured separately according to a die-cutting process wherein thesingle layer antenna element 230 is die-cut from a larger single-layersheet and battery element 220 is die-cut from a larger tri-layer sheet.Once the circuit elements have been separately formed, they may becontacted to compose the singular tag device. In other embodiments, theantenna element 230 may comprise an anode layer, electrolyte layer and acathode layer. In such an embodiment, both the battery element 220 andcircuit element 230 may be cut from a singular larger sheet in thepredetermined shape of the tag device 210. It may be appreciated thatdie-cutting of thin film layers from larger sheets provides a simple,low-cost manufacturing process as opposed to, for example, specializedprinting or other more complex manufacturing techniques.

In the following, an apparatus having conductive polymers according tosome other embodiments comprising self-compensating polymers aredescribed in reference to FIGS. 6(a)-12(b). As described above withrespect to TABLE 1, only some pairs of redox-active polymers aretechnologically and economically feasible for forming the positive andnegative electrodes of the electrochemical cells. For example, only somepairs have a voltage gap between a cathode with higher redox potentialand an anode with lower redox potential that is large enough to betechnologically and economically feasible. Thus, there is a need toincrease the range of “pairable” redox-active polymers that can be usedin the electrochemical cells. In the technology disclosed herein,embodiments can enable a wider range of possible cell voltages whilestill delivering high energy density of the cell.

Redox active polymers may be categorized based on the type of redoxreactions the polymers are configured to undergo. One category includesn-type redox-active polymers, which can be configured to undergo areversible redox reaction between a neutral state and a negativelycharged state. Another category includes p-type redox-active polymers,which can be configured to undergo a reversible redox reaction between aneutral state and a positively charged state. Yet another categoryincludes bipolar redox-active polymers, where a neutral state can beeither reduced to a negatively charged state or oxidized to a positivelycharged state. In practice, bipolar redox active polymers are ofteneffectively configured as n-type or p-type, depending on the particularoperating potential of the electrode. In the electrochemical reductionreaction of n-type redox-active polymers, a cationic species mayneutralize the negative charge; conversely, in the electrochemicaloxidation reaction of p-type redox-active polymers, anions mayneutralize positive charge.

Such redox active polymers can be used to form electrodes in batterycells. A common battery cell configuration employing redox-activepolymers employ one electrode as a redox-active polymer paired toanother electrode being a metal anode (usually lithium) to produce abattery cell sometimes known as a “rocking-chair” battery. As usedherein and in the industry, a “rocking chair” battery cell, sometimesalso referred to as a “swing” type battery cell, refers to a batterycell in which a single ionic charge transfer species (e.g. Lit) can betransferred back and forth between a negative electrode and a positiveelectrode through an electrolyte during charge-discharge cycles. In oneaspect, a “rocking chair” battery cell configuration can be advantageousin that the electrolyte serves as a conductor of the single ion species(e.g., cation such as Li+ or an anion), and a minimal amount ofelectrolyte serves to maximize the energy density of the entire cell.However, in other configurations in which two or more ionic chargetransfer species are transferred between the electrodes, for example inconfigurations where an n-type negative electrode polymer is paired to ap-type positive electrode, a greater amount of electrolyte may be usedto provide sufficient amounts of both anionic species and cationicspecies to compensate i.e. neutralize the charge at both electrodes,while still delivering sufficient ionic conductivity. Not only does thislower the energy density of the entire cell, but the electrolyte canexperience a significant concentration gradient on charge-dischargecycling. The pairing of an n-type redox-active polymer (e.g. anode) witha p-type redox active polymer (e.g. cathode) can present a significantchallenge because to cycle the battery, the electrolyte contains both 1)cations to compensate for the charge associated with redox process ofthe n-type polymer switching between a neutral and anionic state, and 2)anions to compensate for the charge associated with the redox process ofthe p-type polymer switching between a neutral and cationic state. Thisissue is noted by those skilled in the art (see for example Song et. al,Energy & Environmental Science, 2013, 6, 2280-2301).

This issue may be further clarified by way of the following exampleapproximations of a typical volume of electrolyte that may be used topair an n-type negative electrode polymer to a p-type positiveelectrode. By way of an illustrative example only, the molecular mass ofan example anode redox active system including an n-typepolyanthraquinone (PAQ) can be, for example, 208 g/mol. Such an exampleanode redox active system can be coupled to an example cathode systemincluding a p-type phenothiazine, which can have a molecular mass of198.3 g/mol. Assuming that the density of the polymerized film is 1.2g/ml, the molar volume can be estimated to be on the range of about150-200 cm³/mol (e.g. phenothiazine is 165.25 cm³/mol; PAQ is 173.33cm³/mol). Assuming two electrons per redox center, the molarity of thepolymer electrode is on the order of 10 M (e.g. phenothiazine at 12.1 M;PAQ at 11.54 M). For charge balance resulting in 1 mol of ions for everymole of charge, 12 mols of salt can be used for 1 L of each electrode.Common electrolyte concentrations are between 0.3 M and 1 M electrolytewhich translates to about 40 L of electrolyte to balance the charge(i.e. 12 mol at 0.3 M); 12 mol at 1 M is 12 L. This suggests storing themobile cation Li+ in the anode can result in as much as 15% volumeincrease and storing the mobile anion ClO₄ ⁻ in the cathode can resultin as much as 37% volume increase, ultimately consuming the electrolytefrom the solvent. Based on the inventors' analysis, pairing certainn-type anode and a certain p-type cathode may not be desirable forreasons related to the relatively large volume changes, high electrolytevolume requirements and large charge gradients, among other reasons.Thus, there is a need for redox-active polymer electrodes that does notsuffer from such undesirable characteristics associated with the volumechanges.

Advantageously, by employing one of various embodiments ofelectrochemical cells described herein, relatively small volume changes,relatively low electrolyte volume requirements and relatively smallcharge gradients. In embodiments, the ratio of (molarity of chargebalancing mobile ions in the electrolyte)/(molarity of negativeelectrode active charge centers+molarity of positive electrode activecharge centers) may be <1, e.g., 0.1 to 0.4, 0.4 to 0.7 or 0.7 to 0.9,in a self-compensated cell.

The disclosed technology relates to methods of pairing redox-activepolymer electrodes in a “rocking-chair” type cell, regardless of thetype (i.e., n or p type) of the electrodes, and devices having suchpaired electrodes. That is, the disclosed technology advantageouslyenables battery cells in which both electrodes comprise redox-activepolymers, while the electrolyte contains a single mobile ionic species(i.e., anionic or cationic species) that compensate for the chargeassociated with either or both of the electrodes. Thus, the need for oneionic species (e.g., a mobile cationic species) to compensate for thecharge associated with the redox process of one of the electrodes (e.g.,n-type polymer of an anode switching between a neutral and anionicstate) and another ionic species (e.g., a mobile anionic species) tocompensate for the charge associated with the redox process of anotherone of the electrodes (e.g., p-type polymer of a cathode switchingbetween a neutral and cationic state). It will be appreciated that thisopens up the flexibility and range of “pairable” redox-active polymers,in effect delivering a wider range of possible cell voltages while stilldelivering high energy density of the cell. In addition to providing a“rocking-chair” battery regardless of the type of redox-active polymersthat are paired, the volume of electrolyte is significantly reduced,potentially approaching 40% and alleviating any stability issues of thecell relating to large charge gradients associated with shuttling bothmobile cations and mobile anions between the electrodes and electrolyte.

In one aspect, the present disclosure solves a limitation in pairingp-type and n-type polymers in an electrochemical cell by incorporatingredox-active polymers capable of forming zwitterions. As describedherein, a zwitterion refers to a molecule that has at least onepositive, i.e. cationic charge center and at least one negative, i.e.anionic, charge center that exist simultaneously in the same molecule,such that the molecule as a whole can be in a net charge-neutral state,referred to herein as a zwitterionic state. It will be appreciated thatin zwitterions, a charged atom is bonded to an adjacent atom by one ormore covalent bonds, which is distinguishable from a charged atom of anon-zwitterion such as, e.g., an ionic molecule (e.g., NaCl and NH₄Cl)that is not covalently bonded. Furthermore, in zwitterions, atoms havingopposite charges are not immediately adjacent to one another. When acharge imbalance is created between the at least one positive chargecenter and the at least one negative charge center, the zwitterion canbe in a net charged state, referred to herein as a non-zwitterionicstate. In a non-zwitterionic state, the net charge of the zwitterion canbe balanced by an extrinsic charged atom or molecule, e.g., a mobilecation or a mobile anion.

As commonly understood in the industry, a polymer comprises a sequenceor a chain of repeating groups of atoms linked to each other by primary,e.g., covalent bonds. As used herein, a polymer unit refers to a segmentof the polymer chain, e.g., one or more groups of atoms that can berepeated to form longer chains. In various embodiments, a polymercomprises two or more such groups of atoms and can comprise as few astwo such groups (i.e., a dimer), and a polymer unit can comprise as fewas one group (i.e., a monomer). As used herein, “self-compensating”refers to a charge compensating mechanism in a polymer unit whereby,during a charge-discharge cycle of a battery cell comprising the polymerunit in an electrode, a change in the charge state of the polymer unit,which may result from switching between redox states (i.e. by gaining orlosing one or more electrons), is internally compensated within thepolymer unit itself. In contrast, in non-self-compensating polymers, achange in the charge state of a polymer unit may be compensated notwithin the polymer unit itself but through one or more mobiles ion fromoutside of the polymer unit itself, e.g., from the electrode of oppositepolarity and/or the electrolyte material. In various embodiments, someself-compensating polymer units are configured to form a zwitterion,which may be referred to herein as zwitterionic polymer units.

A distinction between a self-compensating n-type polymer unit and anon-self-compensating n-type polymer unit is illustrated via FIGS.6(a)-6(b) and 7(a)-7(b). Referring to the negative electrode 312illustrated in FIGS. 6(a) and 6(b), during a charge-discharge cycle of abattery cell 310 a/310 b having a non-self-compensating n-type polymerunit 314 a/314 b, the n-type polymer unit 314 a/314 b undergoes a redoxreaction between a neutral state 314 b and a negatively charged anionicstate 314 a. The n-type polymer unit 314 a/314 b in the anionic (i.e.,negatively charged) state 314 a may be compensated by a mobile cation(e.g., M⁺ in the negative electrode 312 of FIGS. 6(a) and 6(b)). Incomparison, referring to the negative electrode 332 illustrated in FIG.2, during a charge-discharge cycle of a battery cell 330 a/330 b havinga self-compensating n-type polymer unit 334 a/334 b, comprising e.g., azwitterionic polymer unit according to some embodiments, the n-typepolymer unit 334 a/334 b switches between a cationic state 334 b and a“net neutral” state 334 a, where the “net neutral” state comprises azwitterionic state. In the zwitterionic state, a negative charge of theredox center (e.g. oxygen in anthraquinone) is compensated by thepositive charge center (e.g. R₄N⁺) within the polymer unit itself, thusbeing internally “self-compensated.” That is, in the zwitterionic state,the n-type polymer unit 334 a/334 b forms a charge-neutral unit withouta mobile cation as in FIGS. 6(a) and 6(b). In the cationic state 334 b(i.e. non-zwitterionic state), the positive charge center (e.g. R₄N⁺) ofthe polymer is compensated by a mobile anion (e.g., A⁻ in the negativeelectrode of FIGS. 2(a)-7(b)).

A distinction between a self-compensating p-type polymer unit and anon-self-compensating p-type polymer unit is illustrated via FIGS.6(a)-6(b) and 7(a)-7(b). Referring to the positive electrode 336illustrated in FIG. 7(a)-(b), during a charge-discharge cycle of abattery cell 330 a/330 b having a non-self-compensating p-type polymerunit 338 a/338 b, the p-type polymer unit 338 a/338 b undergoes a redoxreaction between a neutral state 338 b and a positively charged cationicstate 338 a. The p-type polymer unit in the cationic (i.e., positivelycharged) state 338 a may be compensated by a mobile anion (e.g., A⁻ inthe positive electrode of FIGS. 7(a)-7(b)). In comparison, referring tothe positive electrode 316 illustrated in FIGS. 6(a)-6(b), during acharge-discharge cycle of a battery cell having a self-compensatingp-type polymer unit 318 a/318 b comprising a zwitterionic polymer unitaccording to some embodiments, the p-type polymer unit 318 a/318 bswitches between an anionic state 318 b and a “net neutral” state 318 aat the “molecular level,” where the “net neutral” state 318 a comprisesa zwitterionic state. In the zwitterionic state, a positive charge ofthe redox center (e.g. S⁺ in thianthrene) is self-compensated by thenegative charge center (e.g. SO₃ ⁻) within the polymer unit 318 a/318 bitself, thus being “self-compensated.” That is, in the zwitterionicstate, the p-type polymer unit 318 a/318 b forms a charge-neutral unitwithout a mobile anion as in FIGS. 7(a) and 7(b). In the anionic state(i.e. non-zwitterionic state), the negative charge center (e.g. SO₃ ⁻)of the polymer is compensated by a mobile cation (e.g., M⁺ in thepositive electrode of FIGS. 6(a)-6(b)).

In one aspect, various embodiments disclosed herein provides for anelectrochemical energy storage device comprising a negative electroderedox-active polymer film capable of being oxidized during a dischargingoperation. The electrochemical energy storage device further comprises apositive electrode redox-active polymer film capable of being reducedduring a discharging operation. For the purposes of the followingdescription, the term “negative electrode” may be used interchangeablywith the term “anode” or “anodic layer” and, “positive electrode” may beused interchangeably with the term “cathode” or “cathodic layer” todistinguish between the electrodes of the electrochemical energy storagedevice. As described herein, an anode refers to an electrode at which anoxidation reaction occurs thereby producing electrons during a dischargeoperation, and at which a reduction reaction occurs consuming electronsduring a charge operation. Conversely, a cathode refers to an electrodeat which a reduction reaction occurs consuming electrons during adischarge operation, and at which an oxidation reaction occurs therebyproducing electrons during a charge operation. The negative electroderedox-active polymer is characterized by a first redox potential and thepositive electrode redox-active polymer is characterized by a secondredox potential which is greater than the first redox potential. Thenegative electrode active material and the positive electrode activematerial are both electronically conductive and ionically conductive.

In various embodiments described in the following with respect to FIGS.1-3, electrodes of an electrochemical storage device have redox-activepolymer, at least one of which comprises a polymer unit, referred toherein as a zwitterionic polymer unit, that is configured to form azwitterionic state in which charge is self-compensated. As describedabove, above, the zwitterionic polymer unit can be “self-compensated,”which refers to a state of a polymer unit whereby, the charge state ofthe polymer unit, which may result from switching between redox states(i.e. by gaining or losing one or more electrons), is internallycompensated within the polymer unit itself. As described above, azwitterionic polymer unit is configured to form a zwitterionic state,wherein the polymer unit can internally maintain electroneutralitystably by having both cationic and anionic charge centers that existwithin the polymer unit simultaneously. The zwitterionic polymer unitcan alternatively be in a stable non-zwitterionic state (i.e. cationicor anionic state), in which a charge of the polymer unit is compensatedby a mobile counterion species. Unlike the zwitterionic state, in thenon-zwitterionic state, the mobile counterion migrates to and from theopposite electrode through an electrolyte material, e.g., an electrolytelayer, situated between the negative electrode and positive electrode,for example in a separator.

In various embodiments disclosed herein with respect to FIGS. 1-3, anelectrochemical energy storage device comprises an anode comprising anegative electrode active material including a negative electroderedox-active polymer and configured to be oxidized during a dischargingoperation. The device additionally comprises a cathode comprising anactive material including a redox-active polymer and configured to bereduced during the discharging operation. The device further comprisesan electrolyte material interposed between the negative electrode activematerial and the positive electrode active material, the electrolytematerial comprising an ionically conductive polymer and configured toconduct mobile counterions therethrough between the negative electrodeand positive electrode active materials. At least one of the negativeelectrode redox-active polymer and the positive electrode redox-activepolymer comprises a zwitterionic polymer unit configured to reversiblyswitch between a zwitterionic state in which the zwitterionic polymerunit has first and second charge centers having opposite charge statesthat compensate each other, and a non-zwitterionic state in which thezwitterionic polymer unit has one of the first and second charge centerswhose charge state is compensated by one or more of the mobilecounterions.

In some embodiments where one of the negative electrode redox-activepolymer or the positive electrode redox-active polymer comprises azwitterionic polymer unit, the other of the negative electroderedox-active polymer or the positive electrode redox-active polymer doesnot include a zwitterionic polymer unit.

In various embodiments disclosed herein with respect to FIGS. 1-3, theelectrolyte material comprises an ionically conductive polymer film forconducting mobile counterions between the negative electrode and thepositive electrode. The counterion species migrate in and out of thebulk of the polymer and between the negative electrode and positiveelectrode during a discharge operation. In some embodiments, a chargingoperation may be performed such that the negative electrode redox-activepolymer film is reduced and the positive electrode redox-active polymerfilm is oxidized. Exemplary embodiments of various cell configurationswill now be described to illustrate the various configurations andelectrochemical processes.

In a first embodiment, an electrochemical energy storage devicecomprises an anode comprising a negative electrode active materialincluding a negative electrode redox-active polymer and configured to beoxidized during a discharging operation, wherein the negative electroderedox-active polymer is an n-type polymer. The device further comprisesa positive electrode active material comprising a positive electroderedox-active polymer and configured to be reduced during the dischargingoperation. The positive electrode redox-active polymer is a p-typepolymer comprising a zwitterionic polymer unit configured to reversiblyswitch between a zwitterionic state in which the zwitterionic polymerunit has first and second charge centers having opposite charge statesthat compensate each other, and a non-zwitterionic state in which thezwitterionic polymer unit has one of the first and second charge centerswhose charge state is compensated by a mobile cationic species in theanionic state. The device further comprises an electrolyte materialinterposed between the negative electrode active material and positiveelectrode active material, the electrolyte material comprising anionically conductive polymer and configured to conduct the mobilecationic species therethrough from the negative electrode activematerial to the positive electrode active material during thedischarging operation. In some embodiments, the negative electrodeactive material is further configured to be reduced during a chargingoperation, the positive electrode active material is further configuredto be oxidized during the charging operation, and the electrolytematerial is further configured to conduct the mobile cationic speciesfrom the positive electrode active material towards the negativeelectrode active material during the charging operation. The firstembodiment is described in detail with respect to FIGS. 6(a) and 6(b).FIGS. 6(a) and 6(b) depict an electrochemical cell 310 a/310 bcomprising a negative electrode 312 comprising an n-type polymer unit314 a/314 b and a positive electrode 316 comprising a self-compensatedp-type polymer unit 318 a/318 b which includes a self-compensatingzwitterionic polymer unit, undergoing electrochemical redox processesduring (a) a discharge operation and (b) a charge operation,respectively, according to some embodiments.

Referring to the discharge process depicted in FIG. 6(a), the n-typepolymer 314 a/314 b comprises a negative electrode redox active polymerand is configured to be oxidized from an anionic state 314 a towards aneutral state 314 b. As electrons flow from the negative electrode 312to the positive electrode 316 through an external circuit to power the aload 22 (L), mobile cations M⁺ migrate out of the bulk of the negativeelectrode n-type polymer unit 314 a/314 b towards the positive electrodethrough an electrolyte material 320 interposed between the negativeelectrode 312 and positive electrode 316. The positive electrode 316comprises a self-compensated redox-active polymer which during adischarge operation, may be reduced from a zwitterionic state 318 atowards an anionic state 318 b while charge compensation is facilitatedby the mobile counterion M⁺.

Referring to FIG. 6(b), during a charge process, the n-type polymer 314a/314 b comprising the negative electrode redox active polymer isconfigured to be reduced from the neutral state 314 b towards theanionic state 314 a, wherein charge compensation is facilitated by themobile counterion M⁺ migrating out of the bulk of the positive electrode316 comprising the self-compensated p-type polymer unit 318 a/318 btowards the negative electrode 312 through the electrolyte 320.Electrons flow from the positive electrode 316 to the negative electrode312 via an external power source 24 (PS). During the charge process, thepositive electrode 316 comprising the p-type polymer unit 318 a/318 bincluding the self-compensating zwitterionic polymer unit is oxidizedfrom the anionic state 318 b to the zwitterionic state 318 a, whereinthe charge is compensated internally within the polymer unit itself via“self-compensation.”

In a second embodiment, an electrochemical energy storage devicecomprises an anode comprising a negative electrode active materialincluding a negative electrode redox-active polymer and configured to beoxidized during a discharging operation, wherein the negative electroderedox-active polymer is an n-type polymer comprising a zwitterionicpolymer unit configured to reversibly switch between a zwitterionicstate in which the zwitterionic polymer unit has first and second chargecenters having opposite charge states that compensate each other, and anon-zwitterionic state in which the zwitterionic polymer unit has one ofthe first and second charge centers whose charge state is compensated bya mobile anionic species in the cationic state. The device additionallycomprises a positive electrode active material comprising a positiveelectrode redox-active polymer and configured to be reduced during thedischarging operation, wherein the positive electrode redox-activepolymer is a p-type polymer. The device further comprises an electrolytematerial interposed between the negative electrode active material andpositive electrode active material, the electrolyte material comprisingan ionically conductive polymer and configured to conduct the mobileanionic species therethrough from the negative electrode active materialto the positive electrode active material during the dischargingoperation. In some embodiments, the negative electrode active materialis further configured to be reduced during a charging operation, thepositive electrode active material is further configured to be oxidizedduring the charging operation, and the electrolyte material is furtherconfigured to conduct the mobile anionic species from the positiveelectrode active material towards the negative electrode active materialduring the charging operation. The second embodiment is described indetail with respect to FIGS. 7(a) and 7(b). FIGS. 7(a) and 7(b) depictan electrochemical cell 330 a/330 b comprising a negative electrode 332comprising a self-compensated n-type polymer unit 334 a/334 b includinga zwitterionic polymer unit and a positive electrode 336 with a p-typepolymer, undergoing electrochemical redox processes during (a) adischarge operation and (b) a charge operation, respectively, accordingto some other embodiments.

Referring to the discharge process depicted in FIG. 7(a), theself-compensated n-type polymer unit 334 a/334 b including thezwitterionic polymer unit is configured to be oxidized from a neutralzwitterionic state 334 a towards a cationic state 334 b and chargecompensation is facilitated by the mobile counter-anion A⁻. As electronsflow from the negative electrode 332 to the positive electrode 336through an external circuit to power a load 342 (L), the mobile anionsA⁻ migrate out of the bulk of the positive electrode 38 comprising thep-type polymer towards the negative electrode 332 through an electrolytematerial 340. The positive electrode 336 comprises the p-type polymercomprising a redox-active polymer unit 338 a/338 b that is configured tobe reduced from a cationic state 338 a towards a neutral state.

Referring to FIG. 7(b), during a charge process, the n-type polymer unit334 a/334 b comprising the redox-active polymer is configured to bereduced from the cationic state 334 b to the neutral zwitterionic state334 a, wherein charge is compensated internally within the polymer unititself via “self-compensation.” The positive electrode 336 comprises ap-type redox active polymer unit 338 a/338 b that is configured to beoxidized from the neutral state 338 b to the cationic state 338 awherein charge compensation is facilitated by the mobile counterion A⁻migrating out of the bulk of the negative electrode 332 comprising then-type polymer through the electrolyte 340. Electrons flow from thepositive electrode 336 to the negative electrode 332 via an externalpower source 344 (PS).

In a third embodiment, an electrochemical energy storage devicecomprises an anode comprising a negative electrode active materialincluding a negative electrode redox-active polymer and configured to beoxidized during a discharging operation, wherein the negative electroderedox-active polymer is a p-type polymer comprising a zwitterionicpolymer unit configured to reversibly switch between a zwitterionicstate in which the zwitterionic polymer unit has first and second chargecenters having opposite charge states that compensate each other, and anon-zwitterionic state in which the zwitterionic polymer unit has one ofthe first and second charge centers whose charge state is compensated bya mobile cationic species in the anionic state. The device additionallycomprises a cathode comprising a positive electrode active materialincluding a redox-active polymer and configured to be reduced during thedischarging operation, wherein the positive electrode redox-activepolymer is a p-type polymer comprising a zwitterionic polymer unitconfigured to reversibly switch between a zwitterionic state in whichthe zwitterionic polymer unit has third and fourth charge centers havingopposite charge states that compensate each other, and anon-zwitterionic state in which the zwitterionic polymer unit has one ofthe third and fourth charge centers whose charge state is compensated bythe mobile cationic species in the anionic state. The device furthercomprises an electrolyte material interposed between the negativeelectrode active material and the positive electrode active material,the electrolyte material comprising an ionically conductive polymerconfigured to conduct the mobile cationic species therethrough from thenegative electrode active material to the positive electrode activematerial during the discharging operation. In some embodiments, thenegative electrode active material is further configured to be reducedduring a charging operation, the positive electrode active material isfurther configured to be oxidized during the charging operation, and theelectrolyte material is further configured to conduct the mobilecationic species from the positive electrode active material towards thenegative electrode active material during the charging operation. Thethird embodiment is described in detail with respect to FIGS. 8(a) and8(b). FIGS. 8(a) and 8(b) depict an electrochemical cell comprising anegative electrode 352 comprising a first self-compensated p-typepolymer unit 354 a/354 b including a first zwitterionic polymer unit anda positive electrode 356 comprising a second self-compensated p-typepolymer unit 358 a/358 b including a second zwitterionic polymer unit,undergoing electrochemical redox processes during (a) a discharge and(b) a charge operation, respectively, according to yet some otherembodiments.

Referring to the discharge process depicted in FIG. 8(a), the firstself-compensated p-type polymer unit 354 a/354 b of the negativeelectrode 352 is configured to be oxidized from an anionic state 354 ato a neutral zwitterionic state 354 b, wherein charge is compensated bymobile counterion M⁺. As electrons flow from the negative electrode tothe positive electrode through an external circuit to power a load 362(L), mobile cations M⁺ (e.g. H⁺, Li⁺) migrate out of the bulk of thenegative electrode 352 towards the second p-type polymer 358 a/358 b ofthe positive electrode 356 through the electrolyte material 360interposed between the negative electrode 352 and positive electrode356. The second p-type polymer 354 a/354 b of the positive electrode 356is configured to be self-compensated as it is reduced towards theanionic state 358 b while charge compensation is facilitated by themobile counterion M⁺.

Referring to the charge process depicted in FIG. 8(b), the firstself-compensated p-type polymer unit 354 a/354 b of the negativeelectrode 352 is reduced from a neutral zwitterionic state 354 b towardsthe anionic state 354 a, wherein charge compensation is facilitated bythe mobile counterion M⁺ migrating out of the bulk of the positiveelectrode 356 p-type polymer towards the negative electrode 352 throughthe electrolyte material 360. Electrons are conducted from the positiveelectrode to the negative electrode via an external power source 364(PS).

The present disclosure facilitates the pairing of any p-type and n-typepolymers in an electrochemical cell by incorporating any redox-activepolymer configured to form a zwitterionic into at least one of thep-type and n-type polymers. Thus, a wide range of redox-active polymersmay be employed. Furthermore, providing certain zwitterionic polymerunits allows one to tune the system specifically for redox potential.

Advantageously, in various embodiments of electrochemical energy storagedevices (e.g., battery cells) the mobile counterion comprise a singlemobile ionic species that compensates charge states associated withnon-zwitterionic states of one or both of the negative electroderedox-active polymer and the positive electrode redox-active polymer.Thus, the need for one ionic species (e.g., a mobile cationic species)to compensate for the charge associated with the redox process of one ofthe electrodes (e.g., n-type polymer of an anode switching between aneutral and anionic state) and another ionic species (e.g., a mobileanionic species) to compensate for the charge associated with the redoxprocess of another one of the electrodes (e.g., p-type polymer of acathode switching between a neutral and cationic state). That is, when amobile cationic species is present, mobile anionic species may not bepresent, while when a mobile anionic species is present, mobile cationicspecies may not be present. These characteristics enable a substantialreduction in volume changes, as described above.

In some embodiments, the negative electrode redox-active polymer has afirst redox potential and the positive electrode redox-active polymerhas a second redox potential greater than the first redox potential bygreater than about 200 mV, greater than about 600 mV, or greater thanabout 1V.

In some embodiments, the negative electrode active material and thepositive electrode active material each has an electrical conductivitygreater than about 10⁻⁶ S/cm, greater than about 10⁻⁴ S/cm, or greaterthan about 10⁻³ S/cm.

In some embodiments, the negative electrode active material and thepositive electrode active material each has an ionic conductivitygreater than about greater than about 10⁻⁶ S/cm, greater than about 10⁻⁴S/cm, or greater than about 10⁻³ S/cm.

In some embodiments, the zwitterionic polymer unit comprises astructural group comprising a repeating heterocyclic aromatic structureincluding two heteroatoms para to each other, wherein each of theheteroatoms is selected from the group consisting of oxygen (O),carbonyl, sulfur (S), nitrogen (N), and functionalized N.

In some embodiments, the heterocyclic aromatic structure furthercomprises a compensating substituent, such that the heteroatoms and thecompensating substituent forms the first and second charge centershaving opposite charge states that compensate each other.

In some embodiments, the compensating substituent has relatively highratio of electron withdrawing character or electron-donating characterto substituent mass. Not to be bound by any particular theory, but theelectron withdrawing character may, for example, be informed by aparticular substituent's Hammett parameter. The Hammett parameter is anempirical electronic substituent parameter which describes observedelectronic effects (inductive and resonance electronic effects) that asubstituent imparts to a conjugated structure. The Hammett parameter ispositive if it is electron withdrawing or negative if it is electrondonating.

For example, one may calculate the ratio of Hammett parameter tomolecular weight of a substituent as in the table below:

Hammett Molecular Substituent parameter weight Ratio NO 0.91 26 0.035 CN0.66 26.01 0.02537486 N(CH3)3+ 0.82 44.06 0.01861099 NO2 0.78 460.01695652 CHO 0.42 29.02 0.01447278 COCH3 0.5 43.05 0.0116144 CO2H 0.4545.02 0.00999556 CF3 0.54 69.01 0.00782495 Cl 0.23 35.45 0.00648801 SH0.15 33.11 0.00453035 SO3 0.35 80 0.004375 F 0.06 19 0.00315789 Br 0.2379.9 0.0028786 CH2Cl 0.12 61.49 0.00195154 I 0.18 126.9 0.00141844 H 01.01 0 SCH3 0 35.13 0 NHCHO 0 44.03 0 C6H5 −0.01 77.11 −0.0001297 H2C═CH−0.02 27.05 −0.0007394 Si(CH3)3 −0.07 73.09 −0.0009577 C5H11 −0.15 71.16−0.0021079 NHCOCH3 −0.15 58.06 −0.0025835 n-C4H9 −0.16 57.13 −0.0028006n-C3H7 −0.13 43.1 −0.0030162 i-C3H7 −0.15 43.1 −0.0034803 t-C4H9 −0.257.13 −0.0035008 C2H5 −0.15 29.07 −0.00516 OCH2CH3 −0.24 44.06−0.0054471 OCH3 −0.27 31.04 −0.0086985 CH3 −0.17 15.04 −0.0113032N(CH3)2 −0.83 44.06 −0.0188379 OH −0.37 17.01 −0.0217519 NH2 −0.66 16.02−0.0411985

In some embodiments, the ratio of Hammett parameter to molecular weightof a substituent is between about 0.05 and about −0.05. In some otherembodiments, the ratio of Hammett parameter to molecular weight of asubstituent is less than about 0.05 or greater than about −0.05.

In some embodiments, the ratio of electron withdrawing character tosubstituent mass is selected to be between about 0 and about 0.10, orbetween about 0 and about 0.05. In some embodiments, the ratio ofelectron donating character to substituent mass is selected to bebetween about 0 and about −0.10, or between about 0 and about −0.05.

In some embodiments, the compensating substituent is selected to form acharge stabilizing structure. In an embodiment, R of the compensatingsubstituent may be selected to form a six-membered ring in thezwitterionic compensated structure, thereby imparting stability. Forexample, if the heteroatom is located within the in ring structure (e.g.phenothiazine, thianthrene, phenazine) R should be at least two carbonatoms. As another example, or heteroatom outside of ring (e.g. quinonestructures) R should be at least one carbon as depicted below:

The compensating substituent can be selected such that it remains in thecharge state (either anionic or cationic) during battery cycling so thatthe redox active center remains as the heteroatom. In embodiments wherethe compensating substituent is configured to form an anionic species, aredox potential corresponding to a transition of the compensatingsubstituent from an anionic to a neutral state is selected to be greaterthan the a redox potential corresponding to a transition of theheteroatom from a neutral to a cationic state. In embodiments where thecompensating substituent is configured to form a cationic species, aredox potential corresponding to a transition of the compensatingsubstituent from a cationic to a neutral state is selected to be lessthan a redox potential corresponding to a transition of the heteroatomfrom a neutral state to an anionic state.

The redox active polymer is capable of forming a quinoid species withany suitable electron-withdrawing or electron-donating group R1 or R2and polymerized either in the main chain or as a pendant group:

where n is the number of repeated subunits of the polymer having a valuebetween about 1 to about 100,000, between about 10 and about 50,000, orbetween about 25 and about 10,000; P is a suitable conductive polymerbackbone, for example, polyphenylene, polypyrrole, polythiophene,polyaniline, polyacetylenederivative or combinations thereof.

In some embodiments, the at least one of the redox-active polymerscomprise a structural group selected from the group consisting ofquinones, phenothiazines, N-functionalized phenothiazines, thianthrenes,phenozines, phenoxazine, phenoxathiin, dihydrophenazine,dialkyldihydrophenazine, dibenzodioxin, benzofurans, benzodifurans,imides, phthalimides, N-functionalized pthalimides, their derivativesand combinations thereof.

In some embodiments, the zwitterionic polymer unit comprises astructural group selected from the group consisting of:

As described herein, a heteroatom (e.g., N, S) that is functionalizedrefers to a heteroatom having a charge-compensating molecule, referredto herein as a charge compensating substituent, attached thereto. As anexample, the nitrogen atom of N—(CH₂)_(n)—PO₃ is a functionalizedheteroatom, and (CH₂)_(n)—PO₃ is the charge compensating substituent. Invarious embodiments, the heteroatoms and the compensating substituentcan form first and second charge centers having opposite charge statesthat compensate each other.

In these embodiments, W, W′, X, X′, Z and Z′ are heteroatomsindependently selected from the group consisting of oxygen, carbonyl,nitrogen, functionalized nitrogen and sulfur, M is an anion or cationselected from the group consisting of sulfate, phosphate, phosphonate,carboxylate, ammonium, halogenide, sulfonate, hydroxamate,trifluoroborate, acetate, imide, perchlorate, borate, nitro, halogen,cyano, sulfonyl, cyanate, isocyano, sulfonium, phosphonium, carbanionand carborane, and R1 and R2 are independently selected from the groupconsisting of hydrogen, linear or branched and saturated or unsaturatedC1-C6 alkyl or ether chain.

In some embodiments, the zwitterionic polymer unit comprises astructural group selected from the group consisting of:

In these embodiments, each of R, R₁, R′, R″ and R′″ is a hydrogen atomor one of a C1-C6 alkyl chain or a C1-C6 ether chain that is linear orbranched and saturated or unsaturated; and wherein n is the number ofrepeated subunits of the polymer having a value between about 1 to about100,000, between about 10 and about 50,000, or between about 25 andabout 10,000.

In some embodiments, the zwitterionic polymer unit comprises astructural group selected from the group consisting of a PO₃-compensatedphenothiazine polymer, a PO₃-compensated phenothiazine-anilinecopolymer, a PO₃-compensated phenothiazine-thiophene block copolymer, aPO₃-compensated phenothiazine-thiophene random copolymer and aPO₃-compensated phenothiazine-thiophene cross-linked copolymer,represented by respective chemical formulas:

wherein each of m and n is an integer representing repetition ofrespective subunits of the structural group (between 1 and about100,000, between about 10 and about 50,000, or between about 25 andabout 10,000), wherein a ratio of m:n can be between about 0.5 and about2.0, between 0.8 and about 1.2, or between about 0.9 and about 1.1, forinstance about 1:1. It will be understood that, where a copolymer isrepresented as “A_(x)B_(y),” each of x and y independently represents avalue between 1 and about 100,000, between about 10 and about 50,000, orbetween about 25 and about 10,000. Furthermore, the unit “A_(x)B_(y),”itself can repeat such that the polymer is represented as“[A_(x)B_(y)]_(z),” where z has a value between about 1 to about100,000, between about 10 and about 50,000, or between about 25 andabout 10,000.

FIG. 9 depicts an electrochemical cell in a configuration analogous tothat of FIGS. 6(a) and 6(b). In FIG. 9, the left side corresponds to anegative electrode comprising an n-type polymer unit and the right sidecorresponds to a positive electrode comprising a self-compensated p-typepolymer unit which includes a self-compensating zwitterionic polymerunit. In the illustrated embodiment of FIG. 9, the self-compensatingzwitterionic polymer unit includes one of PO₃-compensatedphenothiazine-based polymer molecules disclosed above. Similar to theelectrochemical cell described above with respect to FIGS. 6(a) and6(b), FIG. 9 illustrates the PO₃-compensated phenothiazine-based polymermolecule undergoing electrochemical redox processes between a dischargedstate (upper) and a charged state (lower), respectively, according tosome embodiments.

Similar FIGS. 6(a) and 6(b), in FIG. 9, during a discharge/chargeprocess, the n-type polymer (left) comprising a negative electrode redoxactive polymer and is configured to be oxidized/reduced from/to ananionic state (lower left) to/from a neutral state (upper left). Aselectrons flow between the negative electrode (left) and the positiveelectrode (right), mobile cations (e.g., Lit) migrate through anelectrolyte material (not shown). During the discharge/charge process,the positive electrode (right) comprising the p-type polymer unitincluding the PO₃-compensated phenothiazine-based polymer molecule isreduced/oxidized from/to a zwitterionic state (lower right) to/from ananionic state (upper right). In the zwitterionic state, the charge ofthe PO₃-compensated phenothiazine-based polymer molecule is compensatedinternally within the polymer unit itself via “self-compensation,” whilein the non-zwitterionic (anionic) state the charge is compensated by themobile Li⁺.

In some embodiments, the zwitterionic species may be stabilized by asuitable method. For example, charge screening may be accomplished bythe addition of an additive like a small polar molecule, a lowdielectric additive, a different charge compensating polymer, aderivative or combination thereof. A suitable salt may be mixed in thepolymeric matrix to stabilize and/or screen the charge. As anotherexample, the polymer may be crystallized or otherwise oriented such thatopposite charges of the polymer system is oriented in such a way as tofacilitate charge relaxation.

In some embodiments, the at least one of the negative electrode activematerial and the positive electrode active material further comprises alow dielectric additive configured to screen a zwitterionic charge.Examples of the low dielectric additive include plasticizers, ionicliquids, organic solvents. The low dielectric additive canadvantageously selected to have a dielectric constant less than about10, or less than about 8.

For example, any organic solvent known in the art may be used includingbut not limited to: acetonitrile, n-methyl-pyrrolidione,dimethylformamide, dimethylsulfoxide, tetrahydrofuran, and so on.

For example, any ionic liquid known in the art may be used including butnot limited to: tetramethylammonium salts, or more generallytetraalkylammonium salts, or tetraorganoammonium salts, organoamines,imidazolium salts, pyridinium salts, and so on.

For example, any suitable plasticizer known to those skilled in the artmay be used including but not limited to: Phthalates: Bis(2-ethylhexyl)phthalate (DEHP), Diisononyl phthalate (DINP), Di-n-butyl phthalate(DnBP, DBP), Butyl benzyl phthalate (BBzP), Diisodecyl phthalate (DIDP),Dioctyl phthalate (DOP or DnOP), Diisooctyl phthalate (DIOP), Diethylphthalate (DEP), Diisobutyl phthalate (DIBP), Di-n-hexyl phthalate,Dioctyl terephthalate (DEHT); Trimellitates: Trimethyl trimellitate(TMTM), Tri-(2-ethylhexyl) trimellitate (TEHTM-MG),Tri-(n-octyl,n-decyl) trimellitate (ATM), Tri-(heptyl,nonyl)trimellitate (LTM), n-octyl trimellitate (OTM); Adipates:Bis(2-ethylhexyl)adipate (DEHA), Dimethyl adipate (DMAD), Monomethyladipate (MMAD), Dioctyl adipate (DOA), Dibutyl sebacate (DBS), Dibutylmaleate (DBM), Diisobutyl maleate (DIBM); Sulfonamides: N-ethyl toluenesulfonamide (ortho and para isomers ETSA), N-(2-hydroxypropyl) benzenesulfonamide (HP BSA), N-(n-butyl) benzene sulfonamide (BBSA-NBBS);Phosphates: Tricresyl phosphate (TCP), Tributyl phosphate (TBP);Citrates: Triethyl citrate (TEC), Acetyl triethyl citrate (ATEC),Tributyl citrate (TBC), Acetyl tributyl citrate (ATBC), Trioctyl citrate(TOC), Acetyl trioctyl citrate (ATOC), Trihexyl citrate (THC), Acetyltrihexyl citrate (ATHC), Butyryl trihexyl citrate (BTHC, trihexylo-butyryl citrate), Trimethyl citrate (TMC); Other plasticizers:Benzoates, 1,2-Cyclohexane dicarboxylic acid diisononyl ester,Epoxidized vegetable oils, alkyl sulphonic acid phenyl ester (ASE),Triethylene glycol dihexanoate (3G6, 3GH), Tetraethylene glycoldiheptanoate (4G7).

In some embodiments, the at least one of the negative electrode activematerial and the positive electrode active material further comprises acharge compensating polymer configured to screen a zwitterionic charge.Examples of the charge compensating additives or polymers include ionicliquids, organic solvents (e.g. NMP, acetonitrile), polymer derivativeof small molecule organic solvents, derivatives or combinations thereof.For example, charge compensating polymers may be non-conductivepolyvinylstyrene, polyacrylic acid, polystyrene, polystyrenesulfonate,polyvinylbenzoate, polyvinylbenzohydroxamate, polystenetrifluoroborate,polyanilinesulfone, polyphenylsulfonate, ammonium polystyrene, ammoniumpolyvinylstyrene, derivatives and combinations thereof.

FIG. 10 illustrates cyclic voltammograms showing current-voltagecharacteristics of an electrochemical cell comprising a self-compensatedpolymer which includes a zwitterionic polymer unit, according toembodiments. The illustrated voltammograms were obtained from anelectrochemical cell in a three electrode cell configuration having aPO₃-compensated phenothiazine-aniline copolymer as an active electrodematerial for the working electrode. The solid curve represents aninitial sweep and the dotted curve represents a subsequent sweep after achronoamperometric hold under at 1.7V vs. NHE for one hour to oxidizethe active electrode material, similar to the hold conditions describedwith respect to FIG. 11 below. The electrolyte used was 0.1M lithiumbis(trifluoromethanesulfonyl)imide (LiTFSI) in trimethyl butyl ammoniumTFSI. As illustrated, the redox wave near about 0.7 V (between about 0.6V and 0.8 V) corresponds to the aniline subunit of the copolymer and theredox waves near about 1.4 V (between about 1.3 V and 1.5V) and about1.6 V (between about 1.5 V and about 1.7 V) correspond to thetwo-electron redox process for the compensated phenothiazine subunit ofthe polymer (two peaks visible).

FIG. 11 illustrates chronoamperiometric curves showing current-time(left y-axis) and charge-time (right y-axis) characteristics of anelectrochemical cell comprising a self-compensated polymer whichincludes a zwitterionic polymer unit, according to embodiments. Theillustrated chronoamperiometric curves were obtained from anelectrochemical cell in a three electrode cell configuration having aPO₃-compensated phenothiazine-aniline copolymer as an active electrodematerial for the working electrode. A curve whose value increases withtime represents a current-time curve, while an adjacent curve whosevalue decreases with time represents a corresponding charge-time curve.The current-time/charge-time curve pair on the left represent achronoamperometric hold to oxidize at 1.7V, which was followed by achronoamperomentric hold at 1 volt to reduce, represented by thecurrent-time/charge-time curve pair on the right. In the illustratedembodiment, the resulting charge retention is 54%, which may be lowerthan typical characteristic charge retention for similar systems, giventhe solubility of the active material in the flooded three electrodecell (however in a solid-state battery system, solubility may beavoided) as also evidenced by the smaller peaks in the CV after thechronoamperometirec holds as illustrated in FIG. 10.

FIG. 12A illustrates cyclic voltammograms showing current-voltagecharacteristics of an electrochemical cell comprising an uncompensatedpolymer. By comparison, FIG. 12B illustrates cyclic voltammogramsshowing current-voltage characteristics of an electrochemical cellcomprising a self-compensated polymer which includes a zwitterionicpolymer unit, according to embodiments. The illustrated voltammogramswere obtained from an electrochemical cell in a symmetric cellconfiguration having a PO₃-compensated phenothiazine-aniline copolymeras an active electrode material for the positive electrode. It will beappreciated that the technique employed to obtain the cyclicvoltammograms of FIGS. 12A and 12B allows for an evaluation of thebehavior of each particular electrode in the electrochemical cell byeliminating the effect of the other electrode to which it would beconventionally coupled in a battery. Comparing FIGS. 12A and 7B, thesymmetric cell with an electrode having PO₃-compensatedphenothiazine-aniline copolymer as an active electrode material (FIG.12B) exhibits a relatively fast kinetics with minimal IR drop i.e. sharponset current with onset potential close to zero volts. In contrast, thesymmetric cell with an electrode having an uncompensatedphenothiazine-aniline copolymer as an active electrode material (FIG.12A) exhibits a significant resistance in the cyclic voltammogram. Thecells were assembled in the discharged state. As the potential is sweptaway from zero, charge is added into the cell in an increasing manner.If the potential is kept +/−0.5V subsequent to addition of charge intothe cell, charge transfer between the two identical electrodes in theabsence of side reactions can be observed.

Although this invention has been described in terms of certainembodiments, other embodiments that are apparent to those of ordinaryskill in the art, including embodiments that do not provide all of thefeatures and advantages set forth herein, are also within the scope ofthis invention. Moreover, the various embodiments described above can becombined to provide further embodiments. In addition, certain featuresshown in the context of one embodiment can be incorporated into otherembodiments as well. Accordingly, the scope of the present invention isdefined only by reference to the appended claims.

What is claimed is:
 1. A tag apparatus, comprising: a substrate; a conductive structure formed on the substrate and comprising a layer of redox-active polymer film having mobile ions and mobile electrons, the conductive structure further comprising a first terminal and a second terminal configured to receive an electrical signal therebetween, wherein the layer of redox-active polymer is configured to conduct an electrical current generated by the mobile ions and the mobile electrons in response to the electrical signal; and a detection circuit operatively coupled to the conductive structure and configured to detect the electrical current flowing through the conductive structure. 